Physics 68 Lagrangian Mechanics (4 of 25) Free Fall: Example

In this video I will derive the position with-respect-to time equation of a simple free-fall problem using the partial derivative of Lagrangian equation.

Next video in this series can be seen at:

[pelimies]

I'm just a neighbouring citizen of Sweden, so I cannot present the Nobel for you, but please accept these virtual flowers from the lamemen of the physic-lovers, that are in gratitude for you service to make science indisgestible without signing up to Stanford/MIT/etc.

[drlangattxdotnet]

Hi At 4:31 you substitute +mg when you were supposed to substitute -mg. Am I wrong here? Thanks for great videos.

[auruxy]

As an undergraduate student, your videos are of tremendous help. Thank you so much for dedication of spreading knowledge! Love the videos.

[collegemathematics]

I think you miss a minus sign in 4:30 in the force component.. thank you for these lectures

[niranjanmahajan]

Sir please Do something about Hamilton

[CatsBirds]

Love how you build up as you proceed with your lectures and i am so grateful for you existence.

[lucvelghe]

Very well explained !
Thank you so much, Professor !
(from Belgium)

[Bhaumikpk]

Explained in a skilled manner. Thanks!

[delusiveblaze]

2:28 "because this would require extra work and energy, and that is not going to happen"
What I tell my boss every time he requests me to do anything beyond the initial scope of a task

[allaryyan]

Thank you! I wish professors make it this easy, your effort is deeply appreciated, my exam is tomorrow and you just saved me !

[drlangattxdotnet]

I read the comments and your answer to the sign confusion. I am not sure I understand exactly the reason to switch signs. Great videos.

[subhamchandra]

Sir your lectures are just mindblowing...keep up the gud work...gud wishes from India..❤️❤️

[snegamanjini]

Thank you for the wonderful lectures.. Do you teach in a University or somewhere similar?? If yes, your students are really lucky to have you.. ^^

[hasanshirazi]

Great explanation concise and clear.
One thing I will like to point out is that "g" is always -ve (i.e. g = -9.81 m/s^2) and gravitational potential energy is also always -ve. Hence F = -mg. This will give F=ma in the above example.

[gerritkoenen]

very clear examples, can do this myself now!!

[gabrielgumede]

michel I am lost when you writing the lagrangian the dL\dx is nagative but when u substitute into the lagrangian u leave that nagative and the negative of the lagrangian it self why u left it

[solidstatedevices]

Hats off to this wonderful lecture from another physics teacher !!!

[ptyptypty]

that was amazing... BEHOLD the Power and Beauty of MATH!!

[AN-zkkz]

Thank you Sir for your explanation. I think that the sign of g is wrong, it should be (-) I think.

[stephenobeng]

hello! From the free fall you were saying the kinetic energy increases while potential decreases So how does the lagragian equal -mgy only